Internal combustion engines are still the predominant means for propelling motorized vehicles. They are proven to offer many advantages over alternative mechanisms, among these being cost and convenience. Such engines require lubrication, usually employing a circulating lubricant. In order to achieve good performance, lubricants often include one or more additives which can become depleted and/or insufficient after a period of use. It is desirable to add lubricant additives, such as viscosity index improvers and antioxidants, and the like, to the lubricant to maintain and/or enhance the quality of the lubricant.
Hydraulic fluids are of great value in systems which provide useful mechanical advantages. These hydraulic fluids are employed in such systems often for very long times, for example, in terms of years. Additives which are initially present in the fluid can become depleted and/or insufficient, for example, during long term fluid use. It would be advantageous to provide for adding additives to such hydraulic fluids, in particular while the fluids are in use.
Various methods of introducing additives to vehicle fluid systems, generally, have been proposed. Rohde U.S. Pat. No. 3,749,247 describes a container for releasing an oxidation inhibitor into hydrocarbon-based fluid material in a working engine. The oxidation inhibitor is held in a polyolefin container that permits the additive to permeate through the container wall into the lubricant. A further approach is described by Lefebvre U.S. Pat. No. 5,591,330, which discloses a hydrocarbon oil filter wherein oxidation additives in a thermoplastic material are mounted in a casing between a particle filtering material and a felt pad. Reportedly, the thermoplastic material dissolves in the presence of high temperature oil thereby releasing the additives.
The above-described devices suffer from a variety of limitations. It is an object of the present invention to provide an alternative, relatively low-cost device for releasing chemical additives into a fluid system at a constant rate, which requires minimal human intervention.